A ‘while’ loop repeats as long as some condition is true, so is more appropriate when you want the code to repeat as many times as it takes until a specified condition arises.
Watch this about While Loops: http://www.khanacademy.org/science/computer-science/v/while-loops-in-python
Read this-While Loops: http://en.wikibooks.org/wiki/Python_Programming/Loops
Read this-Conditional Decision Making: http://en.wikibooks.org/wiki/Python_Programming/Conditional_Statement
Then read this-More Conditional Decision Making: https://docs.google.com/previewtemplate?id=1_fgj2LD91iXUwP8ZeeP1pLHkCcC6_2MEbef6-s2EnJ4&mode=public
Then, do these programs (1-7): https://docs.google.com/document/pub?id=1MY68X2XoY9DjI8lefWiMO4kRjBCYSguyxVgCqif6HF0